expo-file-system/src/next/pathUtilities/path.ts

Provides access to the local file system on the device.

// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

function isPathSeparator(code: string) {
  return code === '/';
}

// Resolves . and .. elements in a path with directory names
function normalizeString(path: string, allowAboveRoot: boolean, separator: string) {
  let res: string = '';
  let lastSegmentLength: number = 0;
  let lastSlash: number = -1;
  let dots: number = 0;
  let code: string = '';
  for (let i = 0; i <= path.length; ++i) {
    if (i < path.length) code = path.charAt(i);
    else if (isPathSeparator(code)) break;
    else code = '/';

    if (isPathSeparator(code)) {
      if (lastSlash === i - 1 || dots === 1) {
        // NOOP
      } else if (dots === 2) {
        if (
          res.length < 2 ||
          lastSegmentLength !== 2 ||
          res.charAt(res.length - 1) !== '.' ||
          res.charAt(res.length - 2) !== '.'
        ) {
          if (res.length > 2) {
            const lastSlashIndex = res.lastIndexOf(separator);
            if (lastSlashIndex === -1) {
              res = '';
              lastSegmentLength = 0;
            } else {
              res = res.slice(0, lastSlashIndex);
              lastSegmentLength = res.length - 1 - res.lastIndexOf(separator);
            }
            lastSlash = i;
            dots = 0;
            continue;
          } else if (res.length !== 0) {
            res = '';
            lastSegmentLength = 0;
            lastSlash = i;
            dots = 0;
            continue;
          }
        }
        if (allowAboveRoot) {
          res += res.length > 0 ? `${separator}..` : '..';
          lastSegmentLength = 2;
        }
      } else {
        if (res.length > 0) res += `${separator}${path.slice(lastSlash + 1, i)}`;
        else res = path.slice(lastSlash + 1, i);
        lastSegmentLength = i - lastSlash - 1;
      }
      lastSlash = i;
      dots = 0;
    } else if (code === '.' && dots !== -1) {
      ++dots;
    } else {
      dots = -1;
    }
  }
  return res;
}

function formatExt(ext?: string) {
  return ext ? `${ext[0] === '.' ? '' : '.'}${ext}` : '';
}

export function format(
  sep: string,
  pathObject: {
    dir?: string;
    root?: string;
    base?: string;
    name?: string;
    ext?: string;
  }
): string {
  const dir = pathObject.dir || pathObject.root;
  const base = pathObject.base || `${pathObject.name || ''}${formatExt(pathObject.ext)}`;
  if (!dir) {
    return base;
  }
  return dir === pathObject.root ? `${dir}${base}` : `${dir}${sep}${base}`;
}

export function resolve(...args: string[]) {
  let resolvedPath = '';
  let resolvedAbsolute = false;

  for (let i = args.length - 1; i >= -1 && !resolvedAbsolute; i--) {
    const path = i >= 0 ? args[i] : '';

    // Skip empty entries
    if (path.length === 0) {
      continue;
    }

    resolvedPath = `${path}/${resolvedPath}`;
    resolvedAbsolute = path.charAt(0) === '/';
  }

  // At this point the path should be resolved to a full absolute path, but
  // handle relative paths to be safe (might happen when process.cwd() fails)

  // Normalize the path
  resolvedPath = normalizeString(resolvedPath, !resolvedAbsolute, '/');

  if (resolvedAbsolute) {
    return `/${resolvedPath}`;
  }
  return resolvedPath.length > 0 ? resolvedPath : '.';
}

export function normalize(path: string) {
  if (path.length === 0) return '.';

  const isAbsolute = path.charAt(0) === '/';
  const trailingSeparator = path.charAt(path.length - 1) === '/';

  // Normalize the path
  path = normalizeString(path, !isAbsolute, '/');

  if (path.length === 0) {
    if (isAbsolute) return '/';
    return trailingSeparator ? './' : '.';
  }
  if (trailingSeparator) path += '/';

  return isAbsolute ? `/${path}` : path;
}
export function isAbsolute(path: string) {
  return path.length > 0 && path.charAt(0) === '/';
}
export function join(...args: string[]) {
  if (args.length === 0) return '.';

  const path: string[] = [];
  for (let i = 0; i < args.length; ++i) {
    const arg = args[i];
    if (arg.length > 0) {
      path.push(arg);
    }
  }

  if (path.length === 0) return '.';

  return normalize(path.join('/'));
}
export function relative(from: string, to: string) {
  if (from === to) return '';

  // Trim leading forward slashes.
  from = resolve(from);
  to = resolve(to);

  if (from === to) return '';

  const fromStart = 1;
  const fromEnd = from.length;
  const fromLen = fromEnd - fromStart;
  const toStart = 1;
  const toLen = to.length - toStart;

  // Compare paths to find the longest common path from root
  const length = fromLen < toLen ? fromLen : toLen;
  let lastCommonSep = -1;
  let i = 0;
  for (; i < length; i++) {
    const fromChar = from.charAt(fromStart + i);
    if (fromChar !== to.charAt(toStart + i)) break;
    else if (fromChar === '/') lastCommonSep = i;
  }
  if (i === length) {
    if (toLen > length) {
      if (to.charAt(toStart + i) === '/') {
        // We get here if `from` is the exact base path for `to`.
        // For example: from='/foo/bar'; to='/foo/bar/baz'
        return to.slice(toStart + i + 1);
      }
      if (i === 0) {
        // We get here if `from` is the root
        // For example: from='/'; to='/foo'
        return to.slice(toStart + i);
      }
    } else if (fromLen > length) {
      if (from.charAt(fromStart + i) === '/') {
        // We get here if `to` is the exact base path for `from`.
        // For example: from='/foo/bar/baz'; to='/foo/bar'
        lastCommonSep = i;
      } else if (i === 0) {
        // We get here if `to` is the root.
        // For example: from='/foo/bar'; to='/'
        lastCommonSep = 0;
      }
    }
  }

  let out = '';
  // Generate the relative path based on the path difference between `to`
  // and `from`.
  for (i = fromStart + lastCommonSep + 1; i <= fromEnd; ++i) {
    if (i === fromEnd || from.charAt(i) === '/') {
      out += out.length === 0 ? '..' : '/..';
    }
  }

  // Lastly, append the rest of the destination (`to`) path that comes after
  // the common path parts.
  return `${out}${to.slice(toStart + lastCommonSep)}`;
}
export function toNamespacedPath(path: string) {
  // Non-op on posix systems
  return path;
}
export function dirname(path: string) {
  if (path.length === 0) return '.';
  const hasRoot = path.charAt(0) === '/';
  let end = -1;
  let matchedSlash = true;
  for (let i = path.length - 1; i >= 1; --i) {
    if (path.charAt(i) === '/') {
      if (!matchedSlash) {
        end = i;
        break;
      }
    } else {
      // We saw the first non-path separator
      matchedSlash = false;
    }
  }

  if (end === -1) return hasRoot ? '/' : '.';
  if (hasRoot && end === 1) return '//';
  return path.slice(0, end);
}
export function basename(path: string, suffix?: string) {
  let start = 0;
  let end = -1;
  let matchedSlash = true;

  if (suffix !== undefined && suffix.length > 0 && suffix.length <= path.length) {
    if (suffix === path) return '';
    let extIdx = suffix.length - 1;
    let firstNonSlashEnd = -1;
    for (let i = path.length - 1; i >= 0; --i) {
      const code = path.charAt(i);
      if (code === '/') {
        // If we reached a path separator that was not part of a set of path
        // separators at the end of the string, stop now
        if (!matchedSlash) {
          start = i + 1;
          break;
        }
      } else {
        if (firstNonSlashEnd === -1) {
          // We saw the first non-path separator, remember this index in case
          // we need it if the extension ends up not matching
          matchedSlash = false;
          firstNonSlashEnd = i + 1;
        }
        if (extIdx >= 0) {
          // Try to match the explicit extension
          if (code === suffix.charAt(extIdx)) {
            if (--extIdx === -1) {
              // We matched the extension, so mark this as the end of our path
              // component
              end = i;
            }
          } else {
            // Extension does not match, so our result is the entire path
            // component
            extIdx = -1;
            end = firstNonSlashEnd;
          }
        }
      }
    }

    if (start === end) end = firstNonSlashEnd;
    else if (end === -1) end = path.length;
    return path.slice(start, end);
  }
  for (let i = path.length - 1; i >= 0; --i) {
    if (path.charAt(i) === '/') {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        start = i + 1;
        break;
      }
    } else if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // path component
      matchedSlash = false;
      end = i + 1;
    }
  }

  if (end === -1) return '';
  return path.slice(start, end);
}
export function extname(path: string) {
  let startDot = -1;
  let startPart = 0;
  let end = -1;
  let matchedSlash = true;
  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  let preDotState = 0;
  for (let i = path.length - 1; i >= 0; --i) {
    const code = path.charAt(i);
    if (code === '/') {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        startPart = i + 1;
        break;
      }
      continue;
    }
    if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // extension
      matchedSlash = false;
      end = i + 1;
    }
    if (code === '.') {
      // If this is our first dot, mark it as the start of our extension
      if (startDot === -1) startDot = i;
      else if (preDotState !== 1) preDotState = 1;
    } else if (startDot !== -1) {
      // We saw a non-dot and non-path separator before our dot, so we should
      // have a good chance at having a non-empty extension
      preDotState = -1;
    }
  }

  if (
    startDot === -1 ||
    end === -1 ||
    // We saw a non-dot character immediately before the dot
    preDotState === 0 ||
    // The (right-most) trimmed path component is exactly '..'
    (preDotState === 1 && startDot === end - 1 && startDot === startPart + 1)
  ) {
    return '';
  }
  return path.slice(startDot, end);
}
export function parse(path: string) {
  const ret = { root: '', dir: '', base: '', ext: '', name: '' };
  if (path.length === 0) return ret;
  const isAbsolute = path.charAt(0) === '/';
  let start;
  if (isAbsolute) {
    ret.root = '/';
    start = 1;
  } else {
    start = 0;
  }
  let startDot = -1;
  let startPart = 0;
  let end = -1;
  let matchedSlash = true;
  let i = path.length - 1;

  // Track the state of characters (if any) we see before our first dot and
  // after any path separator we find
  let preDotState = 0;

  // Get non-dir info
  for (; i >= start; --i) {
    const code = path.charAt(i);
    if (code === '/') {
      // If we reached a path separator that was not part of a set of path
      // separators at the end of the string, stop now
      if (!matchedSlash) {
        startPart = i + 1;
        break;
      }
      continue;
    }
    if (end === -1) {
      // We saw the first non-path separator, mark this as the end of our
      // extension
      matchedSlash = false;
      end = i + 1;
    }
    if (code === '.') {
      // If this is our first dot, mark it as the start of our extension
      if (startDot === -1) startDot = i;
      else if (preDotState !== 1) preDotState = 1;
    } else if (startDot !== -1) {
      // We saw a non-dot and non-path separator before our dot, so we should
      // have a good chance at having a non-empty extension
      preDotState = -1;
    }
  }

  if (end !== -1) {
    const start = startPart === 0 && isAbsolute ? 1 : startPart;
    if (
      startDot === -1 ||
      // We saw a non-dot character immediately before the dot
      preDotState === 0 ||
      // The (right-most) trimmed path component is exactly '..'
      (preDotState === 1 && startDot === end - 1 && startDot === startPart + 1)
    ) {
      // eslint-disable-next-line no-multi-assign
      ret.base = ret.name = path.slice(start, end);
    } else {
      ret.name = path.slice(start, startDot);
      ret.base = path.slice(start, end);
      ret.ext = path.slice(startDot, end);
    }
  }

  if (startPart > 0) ret.dir = path.slice(0, startPart - 1);
  else if (isAbsolute) ret.dir = '/';

  return ret;
}
export const sep = '/';
export const delimiter = ':';